Q13 of 38 Page 93

Study the following passage:

Most of the vertebrates have jaws with teeth. The mode of arrangement of teeth on the jaws is called dentition.


The various types of teeth seen in mammals are incisors(I) canines (C) premolars (P) and molars (M). They are used for biting, tearing, chewing and grinding respectively.


Canines, the tearing teeth are well-developed in carnivores and ill-developed or absent in herbivores.


Now answer the following questions:


i) In frogs, all the teeth in the upper jaw look alike, whereas in human beings they are different. The type of dentition in man can be called__________.


a) Homodont


b) Isodont


c) Heterodont


d) Acrodont


ii) The dental formula of a mammal is written as ICPM =2023/1023. The teeth missing in it are _________ .


a) incisors


b) b) canines


c) c) premolars


d) d) molars


i) This type of dentition in man is known as heterodont dentition. They have 2 sets of teeth throughout their life span (milk teeth and permanent teeth) and 4 kinds of teeth- incisors, canines, molars and premolars.


ii) b) Canines


Dental formula is defined as an expression of number of teeth of each type in one half of upper and lower jaw. Dental formula of a mammal is 2123/2123. Incisors-2, canines-1, Premolars-2, Molars-3 in each half of upper and lower jaw.


More from this chapter

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11

i) What are the structural and functional units of kidney?

ii) Arrange the organs of the human excretory system in the correct order, based on the passage of urine.


Ureter, Urethra, Kidney, Urinary bladder


 12

Observe the following flow-chart depicting blood-circulation in mammals.


Pick out the correct blood vessels A, B, C, D from the following:


i) Pulmonary veins


ii) Venacava


C. Pulmonary artery


D. Aorta


Among the P,Q,R and S samples, identify the correct match from the following


a) P & Q = Oxygenated and R& S = Deoxygenated


b) P & Q = Deoxygenated and R& S = oxygenated


c) All are Oxygenated


d) All are Deoxygenated


 14

Fill in the empty boxes with suitable answers with respect to the valves of a mammalian heart.

 15

Any change in the lifestyle, the food habits and the body form of an organism in order to make it comfortable in the environment / habitat, is called adaptation. Identify the suitable adaptation given below against each mammal.

i) conservation of body heat in large marine mammals like whale (Jaws are modified into baleen plates / Forelimbs are modified into flippers /


Fat is deposited in subcutaneous tissue.)


ii) Locating food source by bats-( Forelimbs are modified into wings / Hanging upside down using legs / Production of sounds and detection of the echo)